Synthesis of various substituted dibenzo[b,d]pyranones including amino acid derivatives by SRN1 methodology

An easy prepn. of the title compds. involving a SRN1 o-arylation of phenolates by o-bromobenzonitrile followed by SiO2-catalyzed lactonization is described. Activated or not activated phenols are efficient. Access to benzonaphthopyranones is exemplified by the reactions with 2-naphtholate. Reactions with chiral p-hydroxyphenylamino acid derivs. are also reported. Thus, irradn. of Ac-L-Tyr(Ac)-OMe and 2-bromo-4,5-dimethoxybenzonitrile in liq. NH3, followed by treatment with silica in CH2Cl2, gave 52% dibenzopyranyl amino ester I. [on SciFinder (R)]